Booster for hydraulic pressure systems



April 26, 1949. E, R, PRlCE BOOSTER FOB HYDRAULIC PRESSURE SYSTEMS Filed NOV. l5, 1947 IN VEN TOR. 54H RPAP/f atented Apr. 26, 1949 BOOSTER FOR HYDRAULIC PRESSURE SYSTEMS Earl R. Price, South Bend, Ind., assignor to Bendix Aviation Corporation, South Bend, Ind., a cor-` poration of Delaware Application November 15, 1947, Serial No. 786,231

Claims. 1

This invention relates to boosters for hydraulic pressure systems, such as might be used, for example, in applying vehicle brakes. The booster unit is of the type which is connected to the master cylinder and to the wheel cylinders, or motors, by hydraulic lines and which is actuated by displacement of fluid from the master cylinder, the master cylinder pressure assisting the booster-developed pressure in applying the brakes.

, An object of the present invention is to provide an improved booster unit of the type mentioned in the preceding paragraph, wherein the cost of manufacturing the unit is lessened, and at the same time the overall dimensions of a unit hav-- ing a given capacity are reduced, Cost reduction is obtained by minimizing the number of parts in the booster unit, for example, by eliminating the usual reaction diaphragm associated with the control valve mechanism and obtaining the reaction directly from the hydraulic fluid in the system.

While units having direct hydraulic reaction have heretofore been proposed, they have always tended to be excessively long because of a separation of the input and output hydraulic chambers. The present invention overcomes this disadvantage by locating certain oi the hydraulic operating parts within the casing of the power cylinder. Furthermore, the present invention makes it possible to arrange the hydraulic operating parts in a new relationship by, in effect, reversing the functions of the piston and cylinder at the input side of the hydraulic part of the booster unit. In particular, an intermediate plunger member is provided which functions as a liquid-displacing plunger on the output side of the booster unit and as a movable cylinder on the input side of the booster unit.

Other objects and advantages oi the present invention will become apparent during the following description of an illustrative embodiment, reference being had therein to the `accompanying drawing, in which the figure is a vertical sectional View of my improved boo-ster unit. The master cylinder and wheel cylinders, to which the booster unit is adapted to be connected, are shown diagrammatically. The size of the hydraulic cylinder which form a part of the booster unit has been exaggerated, in order to provide a clearer showing of the structure.

Referring to the single figure, a conventional master cylinder l2, which is operated by a pedal I4, is hydraulically connected by means of a conduit I6 to the novel booster unit I8. At the outlet side, the booster unit is connected by means 2 of conduit 2|] and branch conduits 22 to wheel cylinders, or motors, 24, which are arranged to operate brakes 25. It will, of course, be readily apparent that the assistance of the booster can be used in any type of control system. Its use-- fulness is in no way limited to braking systems, although that constitutes its most important eld at present. v

The booster unit comprises a power cylinder 28 and a hydraulic cylinder 30. The power cylinder 28 may be of any preferred type, i. e. it may utilize whatever source of power is available. In the illustrated version of the invention, the power cylinder is of the diierential air pressure type, and is specically a vacuum power cylinder in which the maximum pressure differential across the piston is provided by having vacuum on one side of the piston and air at atmospheric pressure on the other side of the piston. The

. power cylinder casing may comprise two cupshaped shells 3| and 32, which have peripheral nanges 34 secured together by a plurality of fastening members 36. A pressure responsive movable wall, or piston, 38 divides the power cylinder casing into two chambers 40 and 42, the periphery of piston 38 being sealed by means of a, flexible disphragm .44, the outer circumference of which is secured between the anges 34 of shells '3l and 32, and the inner circumference of which is secured to the piston 38.

The hydraulic cylinder 38 consists of a hollow tubular member 46, which is mounted on the upper end of the power cylinder, and which has a discharge port 48 at its upper end adapted to be. connected to conduit 20.

Mounted on the lower end, or wall, of power cylinder 28, is a hollow stationary piston member 50. Piston member 5i] extends into the interior of the power cylinder toward the hydraulic cylinder 30, and is secured to shell 3l by means of a threaded clamp 52 which engages the threaded end portion 54 of the stationary piston member. In order to permit a certain amount of angular movement of stationary piston member 5|! relative to the power cylinder while at the same time providing a seal at the entrance of chamber 40, a rubber washer 56 is pl-aced between clamp 52 and the power cylinder casing. Provision for possible angular movement of stationary piston member 5G is necessary in order to compensate for any misalignment of the moving parts of the booster unit due to manufacturing tolerances.

A floating plunger member 58 encircles member and extends through the center of the power cylinder. Plunger member 58 has a tubumesme differential is developed -overpower piston 38, moving the piston upwardly, overcoming the resistancev of return spring 98. Movement of power piston 38 on its upward stroke causes piston member 9D to displace hydraulic iluid from chamber lli,v thereby assisting in applying the brakes. The total work done in applying the brakes is the sum of the work done by manually operated plunger member 58 and by power operated piston member 90.

The operator, when depressing the pedal I4, receives a reaction, or feel, which resists operation of the pedal with a force less than, but proportional to, the force exerted on the brakes. The ratio of the pressure per unit area developed in master cylinder I2 to the pressure per unit area developed in chamber 'i5 is equal to the ratio of the effective area or" end portion E2 of plunger member 58 to the eective area of wall 64 of said plunger member. Another way of stating the same thing is to say that the manually developed pressure in master cylinder I2 results in a higher unit pressure in chamber 16, owing to the difference in the areas of wall 64 and end portion 62 of plunger member 58. The additional displacement of hydraulic uid required to satisfactorily operate the brakes is provided by the poweli-operated annular piston 90.

,As the members 58 and 96 move upwardly on their pressure stroke, additional fluid must be displaced from master cylinder I2 in order to hold valve I I4 in open position. As soon as movement of pedal Ill ceases, the power piston 38 overtakes plunger member 58 and brings the control valve mechanism to lapped position, in which both valve elements I I4 and I ID are closed, the booster unit being maintained at the selected stage of operation.

When pressure on pedal I4 is removed, the pressure in chamber 66 will be reduced, and plunger member 58 will be urged downwardly both by spring IGZ and by the pressure in chamber 16. This movement of plunger member 58 will permit spring |26 to unseat valve member IIB, connecting chamber i0 to the vacuum source. When the pressures in chambers and .12 of the power cylinder have been equalized, the return spring 98 will retract power piston 38, bringing with it annular piston gli. The entire assembly will return to released position, with the parts in the hydraulic system to be compensated for by the master cylinder reservoir.

If, when it is desired to operate the brakes, the power piston 33 should, for any reason fail to operate, the brakes will be applied by hydraulic fluid displaced from master cylinder I2, which will pass through passages 'I2 and 14, unseating valve 18, if necessary. Movement of plunger member 58 relative to piston member 99 is limited by the shoulder I34 provided on piston member 9B. Therefore, if it is desired to displace additional uid after maximum power has been developed by the power cylinder, additional master cylinder pressure can force plunger member 58 into engagement with shoulder I3@ and move the entire fluid-displacing assembly.

"From the foregoing description, it will be seen that a large percentage of the working parts of the booster unit have been placed inside the conrines of power cylinder 28. For given displacement and pressure output requirements, my improved booster unit can be incorporated in va much shorter space than any previous booster units of the hydraulic reaction type. Furthermore, it will befapparent that theentireV assembly is so designed and arranged yas to be compact in structure and relatively inexpensive to manufacture. l.

Although this invention has been described in connection withla certain specinc embodiment, the principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art.

, I claim:

l. For use in a hydraulic pressure system which includes a master cylinder and a motor, a booster unit comprising a differential airpressure power cylinder, a hydraulic cylinder mounted on one end of the power cylinder, said hydraulic cylinder having a discharge port adapted to be connected to the motor, a hollow stationary piston member secured to the opposite end of the power cylinder and extending into the interior of the power.

cylinder toward the hydraulic cylinder, said stationary piston member having an inlet port adapted to be connected to the master cylinder, a iloating plunger member having a tubular portion into which said stationary piston member extends and having a reduced diameter substantially solid end portion extending into the aforementio-ned hydraulic cylinder, the inside front wall or the floating plunger member which is formed where the tubular portion joins the end portion being acted upon by the pressure of the hydraulic fluid which passes through the hollow stationary piston member, the end portion of said floating plunger member having a passage therethrough which in released position permits communication between the master cylinder and the motor, a spring-pressed valve member carried by the oating plunger member which closes said passage when the latter member moves on its pressure stroke, a pressure-responsive movable wall in the power cylinder having a central opening through which the stationary piston member and the floating plunger member extend,

" said pressure responsive movable wall dividing the power cylinder into two chambers, two valves operatively associated with ports in the movable wall to control the pressure in one of the chambers, a lever which is arranged to control operation of said valves and which is actuated by movement of the oating plunger member relative to the movable wall, and a pist-on member having a tubular portion connected to the movable wall and an annular liduidedisplacing portion extending into the hydraulic cylinder, said annular liquid-displacing portion encircling the end portion of the floating plunger member, the

work of displacing fluid under pressure from the hydraulic cylinder being performed cooperatively bythe power-operated annular portion of the last-named piston member and the master-cylinder-operated end portion of the iloating plunger member.

2. For use in a hydraulic pressure system which includes a master cylinder and a motor, a booster unit comprising a differential air pressure power cylinder, a hydraulic cylinder mounted 0n one end of the power cylinder, said hydraulic cylinder having a discharge port adapted to be connected to the motor, a hollow stationary piston member secured to the opposite end of the power cylinder and extending into the interior of the power cylinder, said stationary piston member having an inlet port adapted to be connected to the master cylinder, a floating plunger member havingI a tubular portion into; which; said-1 stations. ary piston member extends andhaving axreduoedi diameter erldi portion extending into the; afore-lx mentioned hydraulic cy1indertheinside front, Wall of; the floating plunger member-which is formed where the. tubular portion :loir-1S: the. end: portion being acted upon by the pressure oI the. hydraulic fluid whichpassesf-through the hollow stationary pistonfmember-,the end. portion off said floating plunger member having a passenger,tir-leren` through; which in released positionl permits, conn.. munication between the master cylindery andthe motor, a spring-pressed valve member carried by theoating plunger member which olosessaid passage `when the latter member moves on its pressure stroke, a. pressurefresponsiye movable wall in the power cylinderhavinga central open-` ing through which thestationary piston memberl and' the floating plungerl` member extendfsaid pressure responsive movable.: wall; dividing the power cylinder into. two.. chambers, two valves; operatively associated with ports inv the movable wall'I to control the pressure inone ci the chamf bers, an4 elementyvvhich is arranged to controli Qperation of: said valvesand which.. isy actuated ley-movement of the floatingl plunger mem-berl relative to the movable Wall, and a-pistonfmemberhaving a tubular portion connected to. the' mov.-` able, wall" andi aILA annular liquidfdisplacing por,Y tionr extending; into. the; hydraulic cylinder, said: annularliquid-displacing portionencircling the endg portion,v of the iioati-ng plungermemben 3i For use in a hydraulicuressure System. which. includesa master. cylinder-,anda motori a, boosterunitcomprising aA 'power' cylinder, a hydrauliccylinderv mounted Orione end; off' the power cylin. der, said hydraulic cylinder having al discharge port adapted-,to be connected to the motor, a. hol-` low stationary pistone member 'secured' to the opposite endl off the-powercylinden and extendingv into they interior of. the power cylinder; said@ stationary piston member having an 'inlet' portA adapted to be connectedto. the masterv cylinder, a plungery member having a tubular:portion` into. whichI said stationary piston member' extends and having a reduced: diameter end;A portion ex-` tending into the aforementioned 'hydraulicwcyla inder; the'insid'e front Wall'ofsaidplunger, meme. bei" which is formed' where the. tubular.- portion` joins the'ends. portion'. being actedi'uponby the-- pressure ofl the hydraulicl iluid which passes. through the hollow-stationary piston member,- :the end portionof' saidi plunger member havingI a passage` therethrough which"v inreleased position permits communication between the master..y cyli-. inder and themotor; a `valvelmember Whichfclosessaid passage during the pressurestr'oke, a,y pres, sure-responsive movable wall inthe powercylinder having a central openingthrough 'which the sta-Y` tionary piston member andY saidplungermemben extend-, said pressure` responsive l movable-Wall di,- I'

viding. the power cylinder inton tW-o chambers, -valve mechanism adapted' to control the -pressurei in one of the chambers, an clement whichis arf-- ranged to controloperation of.lr said valve mechaniem and which-is' actuated? 'by movement ofi said` plunger-member, andi a pistonimember 4havingja tubular portion connected to the` movable 'wallf and an annular liquidi-displacing.fportioniextends ing into the hydraulic cylinder; sa-ida annular liquid-displacing portion-encircling the end"porton. of said plunger memben @For useinlA a hydraulic pressuresystemwhich.. includes a master cylinder. andfamotor; arboostierv unit comprisingv alpower; cylinder,` ahydraulic, cylinder vmounted on one end' ofi the.. powerlr cyle` indem, said hydraulic cylinderhaving ai discharge,- pert'adapted: to be connected to thewmotorff-a. hollow stationary piston member secured tov the. opposite endi of the power cylinder and extending intort'he interior of,` the powericylinder, said-staf,

ti-onaryvpiston vmember having an inletY port adapted to bey connected to the master.cylinder;y aplunger member having a tfubular portion' into.` wlhi'olr.said,stationaryY piston member extends andi having a reduced diameter end portion extender. ing intot the aforementionedv hydraulic cylinder, the; inside front Wall. of` said plunger member which, is` formed where the tubular portion. joins; theendportion being acted. upon bythe pressure; offthe hydraulic uid whichpasses through thel hollow stationary piston member, a, pressure-respons'ive movable wall in the power cylinder have ingy afcentral openingfthroughwhich the station-o ary; piston member andI said4 plunger member exc--v terid, said pressure responsive movable Wallfdi vidingf the' power cylinder into twoA chambers, Value mechanism adapted to control the pressurei in; one of the chambers, an element whichfis arf-- rangedito control operation of. said valve-mecha nism andwhich is actuatedby` movement of said" plunger. member, and a. piston m'ernberihavingv a. tubular portion connected to the-movable wall; and an annular liquid-displacing portion:extend"-` ing into the hydraulic cylinder, said annular liquid-displacing portion encircling the end portion` offsaidplunger member.-

5'; For usein a hydraulic'pressure/system whichv includes amaster cylinder and a'motony a booster unit' comprising a power cylinder; a hydraulic f cylinderl mounted on one endorv the power cyl"- having a reduceddiam'eter'end'portionextending intol the aforementioned hydraulic cylinder,v the inside. front wall of said plungerme'mber which isformed" Where lthetubular portion joinsf the@ end portion being actedupon by the-pressurel'of' loW stationary piston member, a pressure-responsive movable Wallin the power cylinder'havingla centralv opening through which the-`st`ationarypiston member andsaid plunger member extend;

l valve' mechanism which is adapt-edito controlthef pressure in one oi` thechambers`- and.' which iis actuated by movement of;-s'aidplungermemberaand a; piston member having' a tubular portion connectedv to the movable wall= and; an annular` liquid-displacing portion extending intofthe hy draulic cylinder, said;r annular liquid-displacingv portion encircling the end portion of said plungerI member:

61A booster unit comprising a powercy1inder,

A- a hydraulic cylinder mounted on oneendof; the

power cylinder,` said' hydraulic cylinder 'having-a: discharge port adaptedto be connect-ed,to'I amoton, a stationary 4piston member lsecured' t'of the opposite Aencliof the vpower cylinder andiextendng; into the interior o f the pouverl cylinder, saidstaf, tionaryr piston member having'- a. passage longitudinally therethrough, the outen4 endofywhichais, adapted=to= be connectedgmo a master. cylinder?, a. plunger member-having a tubulanportion into;n which said f stationary piston vmember rextendss and having a reduced diameter end portion extending into the hydraulic cylinder, the inside front wall of said plunger member which is formed where the tubular portion joins the end portion being acted upon by the pressure of the hydraulic fluid which passes through the stationary piston member, the end portion of said plunger member having a passage therethrough which in released position permits communication between the inlet p-ort and the discharge port, a valve member which closes said passage during the pressure stroke, a pressure-responsive movable wall in the power cylinder which divides the latter into two chambers, valve mechanism which is adapted to control the pressure in one of the chambers and which is actuated by movement of said plunger member, and a piston member having a tubular portion connected to the movable wall and an annular liquid-displacing portion extending into the hydraulic cylinder, said annular liquid-displacing portion encircling the end portion of said plunger member.

7. A booster unit comprising a power cylinder, a hydraulic cylinder mounted on one end of the power cylinder, said hydraulic cylinder having a discharge port adapted to be connected to a motor, a stationary piston member secured to the opposite end of the power cylinder and extending into the interior of the power cylinder, said stationary piston member having a passage extending longitudinally therethrough, the outer end of which is adapted to be connected to a master cylinder, a plunger member having ia tubular portion into which said stationary piston member extends and having a reduced diameter end portion extending into the hydraulic cylinder, the inside front wall of said plunger member which is formed where the tubular portion joins the end portion being acted upon by the pressure of the hydraulic fluid which passes through the stationary piston member, a pressure-responsive movable wall in the power cylinder which divides the latter into two chambers, valve mechanism which is adapted to control the pressure in one of the chambers and which is actuated by movement of said plunger member, and a piston member having a tubular portion connected to the movable wall andan annular liquid-displacing portion extending into the hydraulic cylinder, said annular liquid-displacing portion encircling the end portion of said plunger member.

8. A booster unit comprising a power cylinder, a hydraulic cylinder mounted on one end of the power cylinder, said hydraulic cylinder having a discharge port adapted to be connected to a motor, a stationary piston member secured to the opposite end of the power cylinder and extending into the interior of the power cylinder, said stationary piston member having a passage extending longitudinally therethrough, the outer end of which is adapted to be connected to a master cylinder, a plunger member having a tubular portion into which said stationary piston member extends and having a reduced diameter end portion extending into the hydraulic cylinder, the inside front wall of said plunger member which is formed where the tubular portion joins the end portion being acted upon by the pressure of the hydraulic fluid which passes through the stationary piston member, a pressure-responsive movable wall in the power cylinder, valve mechanism which is adapted to control the pressure acting on the movable wall and which is actuated by movement of said plunger member, and a piston member having a tubular portion connected to the movable wall and an annular liquid-displacing portion extending into the hydraulic cylinder, said annular liquid-displacing portion encircling the end portion of said plunger member.

9. A booster unit comprising a power cylinder, a hydraulic cylinder at one end of the power cylinder, said hydraulic cylinder having a discharge port adapted to be connected to a motor, a stationary piston member secured to the opposite end of the power cylinder and extending into the interior of the power cylinder, said stationary piston member having a passage extending longitudinally therethrough, the outer end of which is adapted to be connected to a master cylinder, a plunger member having a tubular portion into which said stationary piston member extends and having a reduced diameter liquid-displacing end portion, said plunger member being acted upon by the pressure of the hydraulic fluid which passes through the stationary piston member, a pressure-responsive movable wall in the power cylinder, valve mechanism which is adapted to control the pressure acting on the movable wall and which is actuated by movement of said plunger member, and a piston member having la tubular portion connected to the movable wall and an annular liquid-displacing portion extending into the hydraulis cylinder and encircling the end portion of said plunger member.

10. A booster unit comprising a power cylinder, a hydraulic cylinder at one end of the power cylinder, said hydraulic cylinder having a discharge port adapted to be connected to a motor, a stationary piston member secured to the opposite end of the power cylinder and extending into the interior of the power cylinder, said stationary piston member having a passage extending longitudinally therethrough, the outer end of which is adapted to be connected to a master cylinder, a plunger member having a tubular portion into 'which said stationary piston member extends and having a reduced diameter liquid-displacing end portion, said plunger member lbeing acted upon by the pressure of the hydraulic iluid which passes through the stationary piston member, a pressure-responsive movable Wall in the power cylinder, and a piston member having a tubular portion connected to the movable wall and an annular liquid-displacing portion extending into the hydraulic cylinder and encircling the end portion of said plunger member.

EARL R. PRICE.

No references cited Certificate of Correction Patent No. 2,468,706 April 26, 1949 EARL R. PRICE t is hereby certiefi that errors appear in the printed specification of the above numbered patent requiring Correction as follows:

Column 1, line 48, for form read forms; column 2, line 27, for disphragm read diaphragm; column 8, line 41, for members read member; line 71, after passage insert etendt'ng;

and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the oase in the Patent Office.

Signed and sealed this 17th day of January, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant Gommz'ssz'omr of Patents. 

